Tumor necrosis factor alpha (hereinafter abbreviated as TNF .alpha.) is a peptide of 157 amino acids, having a molecular weight of about 17,000. TNF .alpha. is a cytokine produced from various cells including activated macrophages.
Although TNF .alpha. is a cytokine showing cytotoxicity against several kinds of tumor cells, subsequent studies revealed that TNF .alpha. has various other activities, and the activities are not only limited to tumor cells but extend to many other normal cells. The diverse effects of TNF .alpha. are markedly enormous. Examples of the TNF .alpha. activities are suppression of lipoprotein lipase activity in adipocytes; expression of human leukocyte antigens (HLA) on blood endothelial cells and fibroblasts; interleukin-1 production by fibroblasts or macrophages; activation of macrophages; induction of colony stimulating factor by fibroblasts, endothelial cells or some tumor cells; inhibition of synthesis of proteoglycans and stimulation of their resorption in cartilage; activation of neutrophils and generation of superoxide; production of procoagulant factor by blood endothelial cells; proliferation of fibroblasts; IL-6 production by fibroblasts; injury of blood endothelial cells; and the like. According to recent studies, TNF .alpha. is recognized as a cytokine involved broadly in vital protection through inflammation and immune response, as described in Vassalli, P., Ann. Rev. Immunol., 10, 411-452 (1992).
On the other hand, it has been found that continuous or excessive production of TNF .alpha. can result in extreme action on normal cells which can cause various diseases. It is also reported in Beutler B., Greenwald D., Hulmes J. D. et al., Nature, 316, 552-554 (1985), Kawakami, M., SEIKAGAKU (Biochemistry), 59, 1244-1247 (1987) that TNF .alpha. is also known as cachectin, which induces cachexia in cancer or infectious diseases (involving catabolic acceleration of total metabolism leading to extreme wasting).
TNF .alpha. is considered to be one of the causes of septic shock and there are many reports on the effectiveness of an anti-TNF .alpha. antibody in septic shock (Starnes, H. F. Jr., Pearce, M. K., Tewari, ., Yim, J. H., Zou, J. C., Abrams, J. S., J. Immunol., 145, 4185-4191 (1990), Beutler, B., Milsark, I. W., Cerami, A. C., Science, 229, 869-871 (1985), Hinshaw, L. B., Tekamp-Olson, P., Chang, A. C. K. et al., Circ. Shock, 30, 279-292 (1990)).
An increased level of TNF .alpha. is also found in the synovial fluid or blood from rheumatoid arthritis patients, as reported in Tetta, C., Camussi, G., Modena, V., Vittorio, C. D., Baglioni, C., Ann. Rheum. Dis., 49, 665-667 (1990).
In recent years, acquired immunodeficiency syndrome (AIDS) has been explosively prevalent all over the world. AIDS is a disease mainly caused by infection with human immunodeficiency virus-1 (HIV). HIV-infected patients are often complicated by opportunistic infections, Kaposi's sarcoma, neurological disorders (CNS disorders), and/or cachexia, etc., and those diseases often cause fatal.
HIV is a retrovirus classified in the subfamily of Lentiviruses. CD4-positive T lymphocytes and monocytes are the major cellular targets for HIV infection, but HIV also infects other various cells such as macrophages, glial cells and the like. HIV-1 infects cells through binding to specific receptors such as CD4, CXCR4, CCR5 and so on that are expressed on the cell surface. As with the life cycle of other retroviruses, HIV-1 RNA in the cells was reverse-transcribed by HIV-1 reverse transcriptase and a viral DNA was integrated into a genomic DNA of the infected cell by HIV-1 integrase. The integrated DNA, called a provirus, has a unique sequence called long terminal repeat (LTR) at both ends. It is revealed that the LTR region is crucial for the transcription activation and the replication of HIV-1.
Control of HIV-1 transcription is complex and involves the interplay of cis-acting viral elements, viral transactivators, and several cellular proteins. These interactions regulate basal levels and induce high levels of viral gene expression. The site of viral RNA synthesis is the cell nucleus, and the template is proviral DNA integrated into host cell genome. Retroviral LTRs are divided into three regions, called U3, R, and U5 respectively. They have distinct functions in transcription. The U3 region of HIV contains basal promoter elements, including a TATAA box for initiation by host cell RNA polymerase II and sites for binding the cellular transcription factor SP1. Additional cis-acting sequences in this region are recognized by several cellular factors that modulate transcription by influencing the rate of initiation. Initiation of viral RNA takes place at U3/R border of the 5'LTR, and 5' ends of these viral transcripts are posttranscriptionally capped with 7-methylguanosine by cellular enzymes.
It is known that in T cells or macrophages stimulated by, e.g., antigens, a lipopolysaccharide, which is one of the main constituents of bacteria, proinflammatory cytokines (TNF .alpha., IL-1 or IL-6) or PMA, signal transduction pathways in cells are activated and unique sets of activated transcription factors increase in the nucleus to accelerate the transcription of HIV (Osborn, L. et al., Proc. Natl. Acad. Sci., USA, 86, 2336-2340 (1989), Poli, G. et al., J. Exp. Med., 172, 151-158 (1990), Poli, G. et al., Proc. Natl. Acad. Sci., USA, 87, 782-785 (1990)). The viral transactivator Tat functions through a cis-acting sequence, designated the tat-response element (TAR), which is located in R region. R-U5 is in the leader sequence of the full-length viral transcript as well as all spliced transcripts. The 3' ends of viral transcripts are defined by the R/U5 border in 3'LTR; signals in U3 and R (AAUAAA and a downstream GU-rich element) are recognized by cellular functions which add poly-A tails to the 3' ends of viral transcripts. Although both LTRs are identical in sequence, retrovirus have mechanisms by which the 5' LTR is used initiation and the 3' LTR signals addition of poly-A tails (Paul A. Luciw; Virology, Third edition chapter 60 Human Immunodeficiency Viruses and Their Replication Field; Lippincott-Raven Publishers, Philadelphia (1996) 1881). The newly transcribed viral RNA comprises regions encoding proteins constituting HIV and is translated into the proteins to produce new virions together with the viral RNA.
It is considered that an agent that inhibits the functions of Tat, the transcription factors, or inhibits their upstream signaltransducers can be a potential inhibitor for HIV-1 replication. As a result, such an agent can be an effective medicine for treating HIV-1 infection.
In several longitudinal studies of HIV-1 LTR sequence in vitro and in vivo, it was shown that the sequence diversity was found in LTR region of laboratory-adapted and clinical isolated viruses, but it is also reported that several binding sites of transcription factor and TAR are highly preserved. Therefore, the rationale of the medicines described above should be extended to most of HIV-1 infection.
It is interesting to note that some of the binding sites of those transcription factors contained in the LTR sequence are also found in the enhancer/promoter region of viral genes, such as Rous sarcoma virus, human cytomegalovirus and simian virus, and in the enhancer/promoter region of various vital genes including TNF .alpha. (Shakhov, A. N., J. Exp. Med., 171, 35-47 (1990)). It is known that the corresponding transcription factors take some role in activation of the transcription of these genes. It is then suggested that some inhibitors of TNF .alpha. production may reduce not only the transcription of TNF .alpha. but HIV by interfering directly/indirectly with the activity of these transcription factors (Li, C. J. et al., Trends in Microbiology, 2(5), 164-169 (1994)).
On the other hand, an abnormally high concentration of TNF .alpha. in blood of AIDS patients is reported (Dezube, B. J. et al., J. Acquir, Immune Defic. Syndr. 5, 1099-1104 (1992), Wright, S. C. et al., J. Immunol, 141(1), 99-104 (1988)). The excessive production of TNF .alpha. in the AIDS patients is another evidence suggesting that TNF .alpha. would be associated with pathological conditions including cachexia, apoptosis of T cells, abnormal B cells proliferation, etc., in addition to the activity of accelerating HIV proliferation. By reducing the level (concentration) of TNF .alpha. in a host, an inhibitor of TNF .alpha. or an inhibitor of production and/or secretion of TNF .alpha. is therefore expected to show not only the activity of inhibiting HIV replication but the activity of improving the pathological conditions of AIDS described above.
In addition, there are many other diseases wherein a high concentration of TNF .alpha. is found in blood and/or tissue, e.g., osteoarthritis (Venn, G., Nietfeld, J. J., Duits, A. J., Brennan, F. M., Arner, E., Covington, M., Billingham, M. E. J., Hardingham, T. E., Arthritis Rheum., 36(6), 819-826 (1993)); multiple sclerosis (Sharief, M. K., Hentges, R., N. Engl. J. Med., 325 (7), 467-472 (1991)); Kawasaki disease (Matsubara, T., Furukawa, S., Yabuta, K., Clin. Immunol. Immunopathol., 56, 29-36 (1990)); inflammatory bowel diseases such as ulcerative colitis or Crohn's disease (Murch, S., Walker-Smith, J. A., Arch. Dis. Child, 66, 561 (1991); Maeda, Y., SHOKAKI-TO-MEN-EKI (Digestive Organ and Immunity), 22, 111-114 (1989)); Behcet disease (Akoglu, T., Direskeneli, H., Yazici, H., Lawrence, R., J. Rheumatol., 17, 1107-1108 (1990)); systemic lupus erythematosus (SLE) (Maury, C. P. J., Teppo, A-M., Arthritis Rheum., 32, 146-150 (1989)); graft versus host disease (GvHD) (Nestel, F. P., Price, K. S., Seemayer, T. A., Lapp, W. S., J. Exp. Med., 175, 405-413 (1992)); multiple organ failure (Fujiwara, T., Kawakami, M., RINSHO-I (Clinician), 17 (10), 2006-2008 (1991)); malaria (Grau, G. E., Fajardo, L. F., Piguet, P. F., et al., Science, 237, 1210-1212 (1987)); meningitis (Waage, A., Halstensen, A., Espevik, T., Lancet, I, 355-357 (1987)); hepatitis (Sugano, K., KANZO (Liver), 33, 213-218 (1992)); non-insulin-dependent diabetes mellitus (NIDDM) (Hotamisligil, G. S., Shargill, N. S., Spiegelman, B. M., Science, 259, 87-91 (1993), asthma, adult respiratory distress syndrome (ARDS), tuberculosis, atherosclerosis, Alzheimer's disease, etc.
As seen from the above publications, it is understood that excessive production of TNF .alpha. sometimes adversely affects the living body. Therefore, further investigation is desired to develop an inhibitor of production and/or secretion of TNF .alpha. or TNF .alpha. inhibitors available for the treatment of these diseases.
As compounds and factors showing an activity of inhibiting TNF .alpha., pentoxifylline, glucocorticoid, protease inhibitors, phospholipase A2 inhibitors, lipoxygenase inhibitors, platelet activating factor (PAF) antagonists, radical scavengers, prostaglandin F.sub.2 or I.sub.2, an anti-TNF .alpha. antibody, thalidomide, etc. are known. However, these compounds or factors are accompanied by side effects because of a diversity of their pharmacological activities. It is therefore required to develop highly safe compounds based on a novel mechanism.
TNF .beta. (lymphotoxin, LT) is also known as a factor belonging to the same family of TNF .alpha.. TNF .beta. is a glycoprotein composed of 171 amino acids, and has homology with TNF .alpha. both in gene structure and amino acid sequence. Further, it is known that both TNF .beta. and TNF .alpha. commonly share the same receptors and have identical biological activities. The enhancer/promoter regions at the upstream of TNF .alpha. and TNF .beta. genes have a common partial sequence to which the same transcriptional factors possibly bind. TNF .beta. may be produced by stimulation with antigen, phorbol ester and mitogen which are known to induce the production of TNF .alpha.. Thus, factors or compounds having an inhibitory activity on the production of TNF .alpha. may also exhibit an inhibitory activity on TNF .beta. (Jongeneel, C. V., Tumor Necrosis Factors; Beutler, B. Ed., Raven Press: New York, 1992, pp. 539-559, Poter, A. G., FEMS Microbiol. Immunol., 64, 193-200 (1990), Pauli, U., Critical Rev. Eukaryotic Gene Expression, 4, 323-344 (1994)).
On the other hand, piperidinylpyrimidine derivatives are described in WO 9426733 and Japanese Patent KOKOKU No. 49-11710. However, these publications do not suggest any TNF .alpha. inhibitory activities. In the description of Chem. Pharm. Bull., 34 (5), 1907-1916 (1986), which is limited to use as intermediates for synthesis, discloses compounds represented by the following formula: ##STR2## (wherein Bz is benzoyl.). No utility of these compounds is disclosed anywhere in the report.